Electronic device and manufacturing method therefor

ABSTRACT

On the back surface of the chip of which a front surface is formed with an electronic circuit, an adhesive film of a shape and dimensions corresponding to at least the back surface of the chip is adhered to obtain the semiconductor chip with the entire back surface covered with the adhesive film. Such a semiconductor chip is obtained by forming a division groove in the front surface of a semiconductor wafer to be divided into plural chips, grinding a back surface of the wafer until the division groove appears to divide the wafer into plural chips, adhering the adhesive film and a dicing tape on the entire back surface of the wafer, and stretching the dicing tape to cut the adhesive film along the division groove.

This application claims priority under 35 U.S.C. § 119 to JapanesePatent Application No. JP2005-265477 filed Sep. 13, 2005, the entirecontent of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technique relating to a device suchas a semiconductor chip, and in particular, relates to a device on aback surface of which an adhesive film is adhered, and to amanufacturing method for the device.

2. Related Art

In recent techniques for semiconductor devices, a stacked package suchas an MCP (Multi-Chip Package) and a SiP (System in Package), in which aplurality of semiconductor chips are stacked, is used effectively inorder to achieve high density and miniaturization. On a back surface ofthe semiconductor chip provided in such a technique, an adhesive filmcalled a DAF (Die Attach Film), which is made of resin is adhered. Withthis adhesive film, the stacked state of the semiconductor chips ismaintained. As a method for manufacturing the semiconductor chip on theback surface of which the adhesive film is adhered, there is a method inwhich the adhesive film is adhered on a back surface of a thinnedsemiconductor wafer, and the semiconductor wafer is divided alongpredetermined division lines called “streets” in the shape of a latticewhile cutting the adhesive film (Japanese Patent Application Laid-openNo. 2004-319829).

In this type of semiconductor chip, mold resin is filled in a peripheryof the semiconductor chip after the chip is mounted on a mounting boardin many cases. However, if the adhesive film does not cover the entireback surface of the semiconductor chip, and if a small part of an edgeof the back surface is exposed, for example, a filler material includedin the mold resin and called “filler” (with a particle diameter of about10 to 20 μm and including silica, for example) may damage the exposedface on which the adhesive film is not adhered or may be pushed into asmall gap between the exposed face and the stacked object, therebycausing cracking or chipping of the semiconductor chips. Especially inthe extremely thin semiconductor chips having thicknesses of 100 μm orless, such a problem is likely to occur.

Furthermore, the adhesive film also functions as an insulating materialin some cases. In this case, if the back surface includes the exposedface which is not covered with the adhesive film as described above, theexposed portion may come into contact with a bonding wire of thesemiconductor chip on the stacked object side, thereby causingelectrical problems such as short circuiting and leakage. Therefore, itis preferable that the entire back surface of the semiconductor chip becovered with the adhesive film.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a devicewith a two-layered structure in which an adhesive film is adhered on aback surface of a chip such as a semiconductor chip, the device having astructure in which the entire back surface of the chip is covered withthe adhesive film, and to provide a manufacturing method for the device.

According to the present invention, there is provided a device with atwo-layered structure which includes a chip having a functional elementon a front surface of the chip and an adhesive film adhered on a backsurface of the chip, in which the adhesive film corresponds to at leastthe back surface of the chip and covers the entire back surface, and anouter periphery of the chip does not protrude from an outer periphery ofthe adhesive film.

With the device of the present invention, the entire back surface of thechip is protected by the adhesive film. Therefore, even if mold resin isfilled in a periphery of the device, filler included in the mold resindoes not enter the back surface of the chip, thereby avoiding problemssuch as damage to the chip by the filler. If the devices of theinvention are stacked, the back surface of the chip is prevented fromcoming into contact with a bonding wire of the device on the stackedside because the adhesive film is interposed. Therefore, electricalproblems such as short circuiting and leakage are prevented.

In the device of the invention, it is essential that the entire backsurface of the chip be covered with the adhesive film. Furthermore, itis preferable that the adhesive film be larger than the back surface ofthe chip and have an extra portion extending from an edge of the backsurface, because the back surface of the chip is further reliably sealedby the adhesive film.

A manufacturing method for the device, according to the presentinvention, is suitable for producing the above device of the inventionand is a manufacturing method for a device with a two-layered structureincluding a chip having a functional element on the front surface of thechip and the adhesive film adhered on the back surface of the chip fromthe wafer on which a plurality of function elements is defined bypredetermined division lines formed in a lattice shape on the frontsurface of the wafer, the method including: a division groove formingstep for forming a division groove in a front surface of a wafer along apredetermined division line, the division groove having a depthcorresponding to a thickness of the chip to be obtained; a protectionfilm adhering step for adhering a protection film on the front surfaceof the wafer; a back surface grinding step for grinding a back surfaceof the wafer until the division groove appears to divide the wafer intothe individual chips; an adhesive film adhering step for adhering theadhesive film on a back surface of the wafer divided into the pluralityof chips and adhering a dicing tape on the adhesive film, the dicingtape supported by an annular frame and being extensible; and an adhesivefilm cutting step for stretching the dicing tape while retaining theframe to thereby cut the adhesive film along the division groove.

In the above manufacturing method, between the back surfaces of theadjacent chips separated from each other in the back surface grindingstep, the adhesive film corresponding to the width of the divisiongroove exists. The adhesive film between the chips is cut, and thereforethe adhesive film tends to be cut at a position slightly outward from anedge of the chip. Therefore, the entire back surface of the chip iscovered with the adhesive film, and an extra portion extending from theedge of the back surface of the chip is likely to be obtained.

In the manufacturing device of the present invention, instead ofstretching the dicing tape as described above, it is possible to obtainthe device by employing an adhesive film cutting step for applying alaser beam to the adhesive film through the division groove to therebycut the adhesive film along the division groove after the adhesive filmadhering step.

With the present invention, it is possible to obtain a device in whichthe entire back surface of a chip is reliably covered with an adhesivefilm. Therefore, it is possible to provide a device of high quality inwhich damage to the chip and electrical problems caused by exposure of apart of the back surface of the chip are prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general perspective view of a semiconductor wafer to bedivided into semiconductor chips, and an enlarged portion is a deviceregion.

FIG. 2 is a schematic side view of a division groove forming step in amanufacturing method according to a first embodiment of the invention.

FIG. 3 is a general perspective view of a dicing device used in thedivision groove forming step.

FIG. 4 is a perspective view of a front surface side of thesemiconductor wafer after the division groove forming step.

FIG. 5A is a perspective view of a back surface side of thesemiconductor wafer on a front surface of which a protection seal isadhered prior to a back surface grinding step, and FIG. 5B is aperspective view of the back surface side of the semiconductor waferafter the back surface grinding step.

FIG. 6 is a schematic side view of the back surface grinding step in themanufacturing method according to the first embodiment.

FIG. 7 is a general perspective view of a grinder used in the backsurface grinding step.

FIG. 8 is a side view of the semiconductor wafer on the back surface ofwhich an adhesive film and a dicing tape are adhered and a state inwhich the semiconductor wafer is set in a dividing device.

FIG. 9 is a side view of a state in which an adhesive film cutting stepis carried out by the dividing device shown in FIG. 8.

FIG. 10 is a perspective view of a state in which an adhesive filmcutting step is carried out in a manufacturing method according to asecond embodiment of the invention and an enlarged portion is asectional view of a state in which a laser beam is applied to theadhesive film.

FIG. 11 is a schematic side view of a back surface grinding step in amanufacturing method according to a third embodiment of the invention.

FIG. 12 is a schematic side view of an internal modified layer formingstep according to the third embodiment.

FIG. 13 is a side view of a state in which an adhesive film and a dicingtape are adhered on the back surface of the semiconductor wafer and astate in which the semiconductor wafer is set in a dividing device inthe third embodiment.

FIG. 14 is a side view of a state in which an adhesive film cutting stepaccording to the third embodiment is carried out.

EMBODIMENTS OF THE INVENTION

Manufacturing methods for the first to third embodiments according tothe present invention will be described below with reference to thedrawings.

1. Manufacturing Method for the First Embodiment

A reference numeral 1 in FIG. 1 designates a disk-shaped semiconductorwafer formed of a silicon wafer or the like. As shown in FIG. 1, on afront surface of the wafer 1, rectangular chip regions 3 are defined bylattice-shaped streets (predetermined division lines) 2. On a frontsurface of each of these chip regions 3, electronic circuits (functionalelements) 4 are formed as shown in an enlarged portion in FIG. 1.

The chip regions 3 are separated from each other by the manufacturingmethod of the present embodiment, and each of the regions becomes a chip6 of a semiconductor chip (device) 5 with an adhesive film and whichwill be described later (see FIG. 9). A thickness of the wafer 1 isgreater than a thickness of the chip 6 to be produced. The embodiment isa method for manufacturing the semiconductor chip with a two-layeredstructure in which an adhesive film such as a DAF is adhered on a backsurface of the chip 6; the manufacturing method will be described belowin the order of the steps. In the following descriptions, a “frontsurface” of the wafer 1 or the chip 6 is defined as a face on which theelectronic circuits 4 are formed and a “back surface” is defined as aface opposite to this front surface and on which the electronic circuitsare not formed.

(1) Division Groove Forming Step

As shown in FIG. 2, the wafer 1 is held on a chuck table 125 with thefront surface facing up. Then, division grooves 7 with depths slightlygreater than the thickness of the chip 6 to be obtained are formed in alattice shape along the streets 2 by a cutting blade 142. FIG. 3 shows adicing device 10 for cutting and dividing the wafer 1 along the streets2 into semiconductor chips and the division grooves 7 can be formed bythis dicing device 10. A method of forming the division grooves 7 bythis dicing device 10 will be described below.

First, a structure of the dicing device 10 shown in FIG. 3 will bedescribed. The dicing device 10 includes a base 100. Provided on thisbase 100 are: a chuck table mechanism 120 for retaining the wafer 1 in ahorizontal orientation and moving it in a cutting feed direction(direction X in FIG. 3); a cutting unit 140 for cutting the frontsurface of the wafer 1 to form division grooves 7; and a cutting unitsupport mechanism 160 for supporting the cutting unit 140 and moving itin an indexing direction (direction Y in FIG. 3). The cutting unit 140is mounted to be movable in an entering direction (direction Z in FIG.3) with respect to the cutting unit support mechanism 160.

The chuck table mechanism 120 is disposed on one end side in thedirection Y on the base 100 and includes: a pair of guide rails 121fixed to the base 100 and extending in the direction X; a moving plate122 slidably mounted onto the guide rails 121; a stage 124 supported onthe moving plate 122 through a cylindrical post 123; a disk-shaped chucktable 125 rotatably mounted onto the stage 124; and a slide mechanism130 for moving the moving plate 122 along the guide rails 121.

The chuck table 125 has a horizontal upper face and is rotated clockwiseor counterclockwise by a rotary driving mechanism (not shown) housed inthe post 123. The chuck table 125 is of a known vacuum chuck type. Inother words, the chuck table 125 is formed with a large number of smallsuction holes communicating with the front surface and the back surface,and air suction ports of a vacuum device (not shown) are connected tothe back surface side. If the vacuum device is operated, the wafer 1 issuctioned and held on the chuck table 125.

The slide mechanism 130 includes a spiral rod 131 disposed between thebase 100 and the moving plate 122 and extending in the direction X, anda pulse motor 132 for driving the spiral rod 131 for rotation. Thespiral rod 131 is screwed into and penetrates a bracket (not shown)formed to protrude from a lower face of the moving plate 122, and it isrotatably supported so as not to be movable in an axial direction. Withthis slide mechanism 130, if the spiral rod 131 is rotated by the pulsemotor 132, the moving plate 122 is moved along the guide rails 121 inthe direction X according to the rotating direction of the rod 131.

The cutting unit support mechanism 160 includes: a pair of guide rails161 disposed and fixed on the base 100 and extending in the direction Yto form a T-shape together with the guide rails 121 of the chuck tablemechanism 120; a moving table 162 slidably mounted onto the guide rails161; and a slide mechanism 170 for moving the moving table 162 along theguide rails.

The moving table 162 is an L-shaped table having a horizontal plateportion 163 and a vertical plate portion 164 rising from one end portionin the direction X of the horizontal plate portion 163 (i.e., right endportion in a view along an arrow F in FIG. 3 and in which the cuttingunit 140 is seen along the direction Y from the end portion on the chucktable mechanism 120 side of the base 100 in this case). A lower face ofthe horizontal plate portion 163 is slidably mounted to the guide rails161.

The slide mechanism 170 has the same structure as the slide mechanism130 of the chuck table mechanism 120 and includes a spiral rod 171disposed between the base 100 and the horizontal plate portion 163 andextending in the direction Y, and a pulse motor 172 for driving thisspiral rod 171 for rotation. The spiral rod 171 is screwed into andpenetrates a bracket (not shown) formed to protrude from a lower face ofthe horizontal plate portion 163 and is rotatably supported so as not tobe movable in an axial direction. With this slide mechanism 170, if thespiral rod 171 is rotated by the pulse motor 172, the moving table 162is moved along the guide rails 161 in the direction Y according to arotating direction of the rod 171.

The cutting unit 140 includes: a cylindrical housing 141 extending inthe direction Y; a disk-shaped cutting blade 142 attached to a tip endon the chuck table mechanism 120 side of the housing 141; and an aligner150 for locating a cutting line along which cutting is carried out bythe cutting blade 142. The cutting unit 140 is mounted to a left face ofthe vertical plate portion 164 of the moving table 162 in a view alongthe arrow F so as to be able to move up and down through a housingholder 165.

The housing holder 165 is slidably mounted to a guide rail 166 formed onthe left face of the vertical plate portion 164 and extending in thevertical direction. The holder 165 is raised and lowered along the guiderail 166 by a raising and lowering mechanism driven by a pulse motor 180fixed onto the vertical plate portion 164. The housing 141 penetratesand is fixed to the housing holder 165. In this way, the cutting unit140 can move up and down with the housing holder 165.

In the housing 141, a spindle extending in the direction Y and a motorfor rotating the spindle (neither of which are shown) are housed. Thecutting blade 142 is fixed to a tip end of the spindle. With an exposedlower portion of the cutting blade 142 rotating with the spindle, thedivision groove 7 is formed in the front surface of the wafer 1.

The aligner 150 is formed of a microscope, a CCD camera, or the like andhas an image pickup portion 151 for capturing an image of a target at atip end of the aligner 150. The aligner 150 is mounted to a tip endportion of the housing 141 in such a manner that the image pickupportion 151 is adjacent to the cutting feed direction (direction Y) ofthe cutting blade 142.

Next, an operation for forming the division groove 7 in the frontsurface of the wafer 1 by using the dicing device 10 having the abovestructure will be described. The dicing device 10 includes a controlmeans for controlling various operations. First, the wafer 1 with itsfront surface facing up is placed on the chuck table 125 of the chucktable mechanism 120 and the vacuum device of the chuck table mechanism120 is operated. As a result, the wafer 1 is suctioned and held on thechuck table 125. Next, the chuck table 125 is moved in the direction Ytogether with the moving plate 122 by the slide mechanism 130 toposition the wafer 1 directly below the image pickup portion 151 of thealigner 150 that has been disposed on a movement line of the chuck table125 in advance.

Then, an image of the street 2 on the front surface of the wafer 1 iscaptured by the aligner 150 and the chuck table 125 is rotated by thecontroller based on the captured image to align the wafer 1 with thecutting blade 142 so that the street 2 extending in one directionbecomes parallel to the direction Y (i.e., a street 2 orthogonal to thisstreet 2 extends in the direction X).

Moreover, with the controller, the image captured by the aligner 150 issubjected to image processing and a cutting operation pattern isdetermined and stored based on the processed image. The cuttingoperation pattern is a combination of an entering feed of the cuttingblade 142 by movement of the cutting unit 140 in the direction Z, acutting feed of the cutting blade 142 by movement of the chuck table 125in the direction X, and indexing of the cutting blade 142 by movement ofthe cutting unit 140 in the direction Y for forming the division groove7 of a slightly greater depth than the thickness of the chip 6 to beobtained in every street 2. An entering depth of the cutting blade 142is set to a value slightly greater than the thickness of the chip 6 tobe obtained as described above.

By means of the controller, the slide mechanisms 130 and 170 and theraising and lowering mechanism driven by the pulse motor 180 areactuated to follow the above stored cutting operation pattern. With therotating cutting blade 142, the division grooves 7 along the streets 2extending in the lattice shape are formed in the front surface of thewafer 1 as shown in FIG. 4.

The division grooves 7 are first formed along the streets 2 extending inthe direction Y by alternately repeating movement of the chuck table 125in the direction Y and movement of the moving table 162 in the directionX. Next, the chuck table 125 is rotated 90°. Then, by alternatelyrepeating movement of the chuck table 125 in the direction Y andmovement of the cutting unit support mechanism 160 in the direction Xagain, the division grooves 7 are formed along the streets 2 orthogonalto the streets 2 along which the division grooves 7 have been formedalready. Thus, the wafer 1 in the front surface of which the divisiongrooves 7 are formed along all the streets 2 shown in FIG. 4 isobtained.

(2) Protection Film Adhering Step

On the entire front surface of the wafer 1 in which the division grooves7 have been formed in the above manner, a protection film 8 is adheredas shown in FIG. 5A. With this protection film 8, the electroniccircuits 4 on the front surface are protected.

(3) Back Surface Grinding Step

Next, a back surface grinding step for grinding the back surface of thewafer 1 to reach the division grooves 7 to separate the chip regions 3as individual chips 6 is carried out. For this step, as shown in FIG. 6,the protection film 8 is brought into close contact with a front surfaceof a chuck table 317 to hold the wafer 1 on the chuck table 317. Then,the exposed entire back surface of the wafer 1 is ground withgrindstones 326 of a grinding wheel 327 until the division grooves 7appear. FIG. 7 shows a grinding device 30 suitable for grinding the backsurface of the wafer 1, and a method for grinding the back surface ofthe wafer 1 by using the grinding device 30 will be described below.

First, a structure of the grinding device 30 shown in FIG. 7 will bedescribed. The grinding device 30 includes a base 310 on which variousmechanisms are mounted. The base 310 includes a table 311 in a shape ofa rectangular parallelepiped which is disposed to be horizontally longso as to form a main body of the base 310 and a wall portion 312extending in a width direction of the table 311 and vertically upwardfrom one end portion in a longitudinal direction of the table 311 (endportion on the back side in FIG. 7). In FIG. 7, the longitudinaldirection, the width direction, and the vertical direction of the base310 are represented by the directions Y, X, and Z, respectively.

In an upper face of the table 311, a recessed area 313 is formed, and astage 314 is provided for reciprocation in the direction Y in thisrecessed area 313. On opposite sides of a moving direction of the stage314, bellows covers 315 and 316 for closing a moving path of the stage314 to prevent grinding swarf from falling in the base 310 are provided.The stage 314 is caused to reciprocate in the direction Y by a drivingmechanism (not shown) and the covers 315 and 316 expand and contract asthe stage 314 moves.

On the stage 314, a chuck table 317 of the vacuum chuck type, which issimilar to the chuck table 125 of the dicing device 10, is rotatablyprovided. The chuck table 317 is moved together with the stage 314toward the wall portion 312 and is positioned in a machining area. Abovethe machining area, a grinding unit 320 is disposed.

The grinding unit 320 is supported through a feed mechanism 330 to beable to move up and down in the direction Z with respect to the wallportion 312. The feed mechanism 330 includes a pair of guide rails 331,a moving plate 332 for sliding along these guide rails 331, and araising and lowering mechanism 333 for raising and lowering the movingplate 332 along the guide rails 331.

The grinding unit 320 includes a block 321 affixed to a front surface ofthe moving plate 332, a cylindrical housing 322 affixed to the block321, a spindle 323 supported in the housing 322, and a servomotor 324for driving the spindle 323 for rotation. To a lower end of the spindle323, a disk-shaped wheel mount 325 is affixed. Moreover, to a lower faceof this wheel mount 325, the grinding wheel 327, to a lower face ofwhich a large number of chip-shaped grindstones 326 made of resin bondor the like are secured is affixed, as shown in FIG. 6. Although anoutside diameter of the grinding wheel 327 is slightly greater than halfof a diameter of the wafer 1 in FIG. 6, the dimension is not limited tothis. The grinding unit 320 and the chuck table 317 are disposed in suchpositions that rotation centers of both of them are arranged in thedirection Y.

Next, the operation for grinding the back surface of the wafer 1 byusing the grinding device 30 having the above structure will bedescribed, the protection film 8 having been adhered on the frontsurface of the wafer 1. First, the wafer 1 is placed on the chuck table317 with its back surface to be ground facing up, and the vacuum deviceis operated to hold the wafer 1 on the chuck table 317. Then, the stage314 is moved to move the wafer 1 into the machining area below thegrinding unit 320. In this case, the stage 314 is moved to a positionsuch that at least a part of the wafer 1 on the wall portion 312 sideand corresponding to a radius of the wafer 1 overlaps the grinding wheel327.

From this state, the chuck table 317 is rotated to rotate the wafer 1.At the same time as this, the grinding wheel 327 of the grinding unit320 is rotated by the servomotor 324 and the grinding unit 320 is slowlylowered at a predetermined speed by the feed mechanism 330. The rotatingdirection of the chuck table 317 may be the same as that of thegrindstones 326 or may be the opposite.

As the grinding unit 320 moves down, the grindstones 326 of the rotatinggrinding wheel 327 press the back surface of the rotating wafer 1 with apredetermined load. Thus, the back surface side of the wafer 1 is groundflat. If grinding of the back surface of the wafer 1 proceeds, thegrindstones 326 eventually reach the division grooves 7, and thedivision grooves 7 appear. If the thickness of the wafer 1 reaches thethickness of the chip 6 to be obtained, the grinding of the back surfaceis completed. As a result of the grinding of the back surface, the wafer1 is divided into a plurality of chips 6 as shown in FIG. 5B. However,because the chips 6 are connected to each other through the protectionfilm 8, they are not separated from each other.

(4) Adhesive Film Adhering Step

Next, an adhesive film 9 is adhered on the back surface of the wafer 1in which the plurality of chips 6 obtained by division are connected toeach other by the protection film 8 as shown in FIG. 8, and a dicingtape 41 placed and supported on an inside of an annular frame 40 isadhered on the adhesive film 9. The adhesive film 9 is made of adhesivematerial having adhesion on opposite faces. As the adhesive material, amixture obtained by properly mixing an additive such as an inorganicfiller into a mixture as a base and a thermoplastic polyimide resin witha glass transition temperature (Tg) of 90° C. or less and athermosetting resin such as an epoxy resin is preferably used, forexample.

As the dicing tape 41, a resin tape which is extensible is used. Forexample, tape formed by applying an acrylic resin adhesive having athickness of about 5 μm to one face of a polyvinyl chloride sheet havinga thickness of about 10 μm as a base material is used, for example. Thedicing tape 41 is in a circular shape having a larger diameter than thatof the adhesive film 9. The frame 40 is adhered on an adhesive side ofan outer peripheral portion of the dicing tape 41, and the adhesive sideon which the frame 40 is adhered is adhered on the adhesive film 9. Suchadhering of the adhesive film 9 and the dicing tape 41 on the backsurface of the wafer 1 can also be achieved by adhering a double-layeredtape obtained by integrally forming the adhesive film 9 with the dicingtape 41.

(5) Adhesive Film Cutting Step

Next, an adhesive film cutting step for cutting the adhesive film 9between the chips 6 to substantially divide the wafer 1 and to yield thesemiconductor chips 5 in which the adhesive film 9 is adhered on theback surface of each individual chip 6 is carried out. For this purpose,a dividing device 50 for the wafer 1 shown in FIG. 8 is used. Thisdividing device 50 includes: a cylindrical base 501; a plurality ofretaining chips 502 fixed at regular intervals in a circumferentialdirection onto an upper end face of the base 501; and a chuck table 504of a vacuum chuck type which is raised and lowered by a raising andlowering mechanism 503. Each retaining chip 502 protrudes inward so thata gap is created between the retaining chip 502 and the upper end faceof the base 501 and the frame 40 can be locked to a lower face of theretaining chip 502. An annular sliding member 505 with a low coefficientof friction is fitted at an outer peripheral edge of an upper end faceof the base 501 to be flush with the upper end face of the base. Thesliding member 505 is made of a material such as stainless steel havinga polished surface, for example.

In order to obtain the semiconductor chip 5 by using the dividing device50, the wafer 1 is placed on the chuck table 504 with the dicing tape 41side facing down, and the frame 40 is positioned under the held chips502 as shown in FIG. 8. Then, the protection film 8 adhered on the frontsurface is peeled off and removed. From this state, the wafer 1 israised by the raising and lowering mechanism 503.

In this way, as shown in FIG. 9, the frame 40 is engaged with theretaining chips 502 and further raising is blocked, the dicing tape 41inside the frame 40 moves up, and as a result, the dicing tape 41 isstretched out radially from the center. As the dicing tape 41 isstretched, the adhesive film 9 between the chips 6 is pulled and is cutalong the division grooves 7. At this time, because the outer peripheraledge of the upper face of the chuck table 504 is formed of the slidingmember 505, the dicing tape 41 smoothly slides on a corner portion ofthe outer peripheral edge and is less likely to receive stress, andthere is very little risk of breakage of the tape 41.

In the above manner, the semiconductor chip 5 with the two-layeredstructure in which the adhesive film 9 is adhered on the back surface ofthe chip 6 as shown in the enlarged portion of FIG. 9 is obtained. Thesemiconductor chips 5 are still adhered on the dicing tape 41 and areafterwards separated one by one from the dicing tape 41 in anappropriate manner.

In the semiconductor chip 5 manufactured as described above, the entireback surface of the chip 6 is covered with the adhesive film 9, and theback surface is protected by the adhesive film 9. Therefore, when thesemiconductor chip 5 is mounted on a mounting board and mold resin isfilled in a periphery of the chip, filler included in the mold resindoes not enter the back surface of the chip 6, thereby avoiding problemssuch as damage to the chip 6 by the filler. If the semiconductor chip 5is applied to a stacked package such as an MCP (Multi-Chip Package) andan SiP (System in Package), the back surface of the chip 6 is preventedfrom coming into contact with a bonding wire of the semiconductor chipon the stacked side, because the adhesive film 9 is interposedtherebetween. Therefore, electrical problems such as short circuitingand leakage are prevented.

Moreover, with the above manufacturing method, between the back surfacesof the adjacent chips 6 separated from each other in the back surfacegrinding step, the adhesive film 9 corresponding to the width of thedivision groove 7 exists. The adhesive film 9 between the chips 6 iscut, and therefore the adhesive film 9 tends to be cut in a slightlyouter position from an edge of the chip 6 (e.g., a center portion of thewidth of the division groove 7). Therefore, the entire back surface ofthe chip 6 is covered with the adhesive film 9 and a surplus portion 9 aof the adhesive film 9 extending from the edge of the back surface ofthe chip 6 is likely to be obtained. Due to the existence of thissurplus portion 9 a, the adhesive film 9 is larger than the back surfaceof the chip 6, and the back surface of the chip 6 is further reliablysealed.

2. Manufacturing Method for Second Embodiment

Next, a manufacturing method for a second embodiment of the inventionwill be described. This manufacturing method is the same as that of thefirst embodiment up until the adhesive film adhering step and differs inthe adhesive film cutting step after the adhesive film adhering step. Inthe adhesive film cutting step in the second embodiment, as shown inFIG. 10, a laser beam is applied to the adhesive film 9 through thedivision grooves 7 from a laser beam irradiation device 60 to therebycut the adhesive film 9 along the division grooves 7. In this way, thesemiconductor chip 5 in which the adhesive film 9 is adhered on the backsurface of the chip 6 is obtained. In order to apply the laser beam tothe adhesive film 9 along the division grooves 7, the laser beamirradiation device 60 is mounted in place of the cutting blade 142 ofthe dicing device 10 shown in FIG. 3 and the aligner 150 controls thelocation at which the laser beam is to be applied.

3. Manufacturing Method for Third Embodiment

Next, a manufacturing method for a third embodiment of the inventionwill be described.

(1) Back Surface Grinding Step

First, the back surface of the wafer 1 shown in FIG. 1 is ground untilthe wafer 1 becomes as thin as the chip 6 to be obtained. For thispurpose, as shown in FIG. 11, the wafer 1 on the front surface of whichthe protection film 8 has been adhered is suctioned and held on thechuck table 317 of the grinding device 30 shown in FIG. 7 with the backsurface of the wafer 1 facing up and the back surface is ground with thegrindstones 326 of the grinding wheel 327.

(2) Inside Modified Layer Forming Step

Then, the laser beam is applied to the insides of the streets 2 of thewafer 1 along the streets 2 to change the portion to which the laserbeam is applied into the inside modified layer. This inside modifiedlayer is a layer that has been melted and set again so that the layer isreduced in strength. The layer is modified so as to break when externalforce is applied to it. In order to form the inside modified layer, asshown in FIG. 12, the wafer 1 is drawn and held on the chuck table 125of the dicing device 10 shown in FIG. 3 with its back surface facing up,and the laser beam is applied to the wafer 1 from the laser beamirradiation device 60 mounted in place of the cutting blade 142. Aposition to which the laser beam is applied is controlled by the abovealigner 150.

(3) Adhesive Film Adhering Step

Similarly to the adhesive film adhering step in the first embodiment,the adhesive film 9 and the dicing tape 41 are adhered on the backsurface of the wafer 1 in which the inside modified layer is formedalong the streets 2 as shown in FIG. 13.

(4) Dividing Step

Next, a dividing step for simultaneously dividing the wafer 1 intoplural chips 6 and dividing the adhesive film 9 so that the separatedfilms correspond to the chips 6 to thereby obtain the individualsemiconductor chips 5 is carried out by utilizing the dividing device 50used in the first embodiment. For this purpose, as shown in FIG. 13, thewafer 1 is placed on the chuck table 504 with the dicing tape 41 sidefacing down and is positioned under the retaining chips 502. Then, theprotection film 8 adhered on the front surface is peeled off andremoved. From this state, the wafer 1 is raised by the raising andlowering mechanism 503.

As a result, as shown in FIG. 14, the frame 40 is retained by theretaining chips 502 and the dicing tape 41 on the inside of the frame 40moves up to thereby radially stretch the dicing tape 41 from the center.As the dicing tape 41 is stretched, the wafer 1 is broken at the insidemodified layer thereof and is divided into chips 6. Moreover, as thedicing tape 41 is stretched, the adhesive film 9 between the chips 6 ispulled and is cut between the chips 6. Division of the wafer 1 into thechips 6 and cutting of the adhesive film 9 may occur simultaneously, orthe adhesive film 9 may be cut after division of the wafer 1 into thechips 6.

With the above second and third embodiments, similarly to the firstembodiment, the semiconductor chip 5 with a two-layered structure inwhich the adhesive film 9 is adhered on the entire back surface of thechip 6 as shown in the enlarged portion of FIG. 9 can be obtained.Therefore, the obtained semiconductor chip 5 has similar effects ofprevention of damage to the chip 6 due to filling of the mold andoccurrence of electrical problems in the stacked state.

1. A device with a two-layered structure, comprising: a chip having afunctional element on a front surface of the chip; and an adhesive filmadhered on a back surface of the chip, the adhesive film correspondingto at least the back surface of the chip and covering the entire backsurface of the chip, an outer periphery of the chip not protruding froman outer periphery of the adhesive film.
 2. The device according toclaim 1, wherein the adhesive film is larger than the back surface ofthe chip and has an extra portion extending from an edge of the backsurface.
 3. A manufacturing method for the device according to claim 1,the method comprising: a division groove forming step for forming adivision groove in a front surface of a wafer along a predetermineddivision line, the division groove having a depth corresponding to athickness of the chip to be obtained; a protection film adhering stepfor adhering a protection film on the front surface of the wafer; a backsurface grinding step for grinding a back surface of the wafer until thedivision groove appears to divide the wafer into individual chips; anadhesive film adhering step for adhering the adhesive film on a backsurface of the wafer divided into plural chips and adhering a dicingtape on the adhesive film, the dicing tape supported by an annular frameand being extensible; and an adhesive film cutting step for stretchingthe dicing tape while retaining the frame to thereby cut the adhesivefilm along the division groove.
 4. A manufacturing method for the deviceaccording to claim 1, the method comprising: a division groove formingstep for forming a division groove in a front surface of a wafer along apredetermined division line, the division groove having a depthcorresponding to a thickness of the chip to be obtained; a protectionfilm adhering step for adhering a protection film on the front surfaceof the wafer; a back surface grinding step for grinding a back surfaceof the wafer until the division groove appears to divide the wafer intothe individual chips; an adhesive film adhering step for adhering theadhesive film on a back surface of the wafer divided into plural chipsand adhering a dicing tape on the adhesive film, the dicing tapesupported by an annular frame and being extensible; and an adhesive filmcutting step for applying a laser beam to the adhesive film through thedivision groove to thereby cut the adhesive film along the divisiongroove.